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RobjUK

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Posts posted by RobjUK

  1. 1 hour ago, tarifa said:

    Try putting a resistance across the the motor wires.

     

    +1 for that idea, before you scrap them!

     

    Add a resistance so the decoder in the dummy unit "sees" some form of load, and see if that makes it work differently. 

    And/or turn off any back EMF option in that decoder - set CV10 to 0 ?

     

    It could be detecting either no current or no back EMF and going in to some form of safety shutdown mode.

     

  2. For information, RJ plugs are each compatible with larger sockets.

     

    You can use RJ45 (ie. Ethernet) sockets with the RJ12 Loconet cables. That may make things a bit more versatile as you can use cheap IDC "punchdown" ethernet sockets and daisy chain the connecting wires through several sockets, or attach them to different parts of a baseboard?

     

    You can also use Ethernet trunk cable for linking the sockets at the IDC side, or ethernet patch cables for linking between sockets on different baseboards.

    Standard Ethernet cables are wired pin to pin.

     

    Basic keystone jacks are very cheap and there are numerous faceplates of different styles to take various numbers.

    eg.

    https://www.ebay.co.uk/itm/10x-RJ45-Keystone-Jack-Wall-End-Plug-Cat-5e-Ethernet-LAN-Network-Module-Adapter/272620577797?hash=item3f7973e405:g:w54AAOSwImRYRqt~

    https://www.ebay.co.uk/itm/RJ45-Network-LAN-Cat-5e-4-Port-Faceplate-Single-Gang-Wall-Socket-Keystone-Jack/272629619364?hash=item3f79fddaa4:g:M-gAAOSwc-tY72U6

    https://www.ebay.co.uk/itm/2-Ports-RJ45-Keystone-Jack-Surface-Mount-Box-White-1-Pack/292689251029?hash=item4425a38ad5:g:DrwAAOSwPeVb53wO

     

     

  3. Does it have a two-digit address, or a four digit starting 00 (or three digit less than 128)?

     

    Some systems get confused between two and four digit and the decoder only responds to the address type it's set for, even if that could be represented in either form.

     

    If there is any possibility of that, you could try explicitly giving it a new, full four digit address and see if that works on both systems?

     

  4. How about cubed foam / pick n pluck inserts?

    They are readily available on ebay, you just make whatever size cavity "nests" you need for the items you will be storing.

     

    eg. Each of these would cut in half and do two of the 4L boxes, if I'm getting the sizes right - so ten box inserts for £15.

    https://www.ebay.co.uk/itm/5x-Pick-Pluck-Foam-Cubed-Insert-Flight-Carry-Camera-Case-Travel-Box/352851661381?hash=item5227991245:m:mB6s8EOPy-CbKB-I7GTOkAw

     

     

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  5. On 26/11/2019 at 06:35, AndyID said:

    The snag is that the torque transmitted is proportional to the speed difference between the input and output so unless there's a lot of slip you don't get much torque.

     

    That reminds me of a gadget I read about some decades ago - a kind of drive unit or "torque converter" using two closely spaced parallel conducting discs connected to the input and output shafts, in a casing filled with mercury and a strong end-to end magnetic field.

    (I can't find the name for the overall system so far, google results are swamped with free energy junk...)

     

    The whole setup forms a homopolar generator directly connected (via the mercury) to a homopolar motor.

     

    If I remember the details in the book correctly, it gives both the direct magnetic drive and a torque increase as "slip" increases, in a similar way to a hydraulic torque converter - a pretty good system for a locomotive drive?

     

    Obviously mercury is not a good idea but galinstan alloy could serve the same purpose, as long as an appropriate metal is available for the discs - aluminium is definitely not suitable for contact with gallium, for one example. Possibly a non-magnetic grade stainless steel would work?

     

    With far stronger neodymium magnets now available, it could be an interesting experiment; it may be possible to scale it to 0 gauge, i don't know about smaller scales though.

     

    • Informative/Useful 1
  6. I've not tried it, but I'd think it may be a bit sloppy, as it's not a particularly tight fit in the outer. It's designed for permanent tension rather than push-pull use.

    Depending how you are operating it, it may be OK, or it may work better with a spring at the far end to help return it.

     

    RC model flexible pushrod "snakes" may be better - they use either a much stiffer wire inner or a plastic rod/tube for the inner.

    eg. https://www.totemhobbies.co.uk/product/accessories/aircraft-accessories/linkages/sullivan-flexible-snake-x-36in-2/

     

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  7. 14 hours ago, Andymsa said:

    I found the motor starting to smoke and a reduction in speed from the previous set top speed. On inspection of the motor it is showing signs of the windings starting to degrade. I will also add this is a brand new loco that has never been run and has sat on the shelf for a number of years.

     

    That could be caused by a weak magnet - the motor efficiency drops off and the current requirements go crazy.

     

    Possibly age, or some older magnet materials can be drastically weakened by impact, eg. if the motor was knocked or dropped in the past, even during original assembly.

     

    • Informative/Useful 1
  8. 8 hours ago, Harry50 said:

    If I use plastite screws, do I design a pilot hole into that is one size smaller than the screw?

     

    I'd size it a few thou larger than the "core" diameter of the thread, or half way between core and outer diameters if you want to play safe.

     

    I've used metric taptites without any problems. They leave a true metric standard thread, rather than the random groove a self tapper cuts.

    This is what they look like:

    https://www.stanleyengineeredfastening.com/-/media/web/sef/resources/docs/other/taptite_2000_brochure_1.ashx

     

    eg. these are they, but RS don't use the name:

    https://uk.rs-online.com/web/p/self-tapping-screws/4831230/

     

     

  9. 9 minutes ago, wasdavetheroad said:

    For the OP, what make radio throttles are you using? I am surprised that they should demand at least 8.5 V, plus is their power requirement in milliamps? A 9v rechargeable probably has less than 200 mAh capacity.

     

    Agreed, it's bad design practice to not allow for the full charge-discharge voltage range of whatever battery it is supposed to use!

     

    As the thing can apparently handle 12V or more from a fully charged 8 cell NiMH PP3, I was thinking that three lithium cells would be a better power source.

     

    They would give a voltage range of 12.6 fully charged to still over 9V end-of-life.

     

    You can get tiny ones for small drones, and multi-cell chargers - make a harness to connect three in series in the controller, but charge them all separately to avoid balance problems, and you should get a good life out of them.

     

    eg. Three of these will fit in the space of a PP3, giving 240mAH capacity at ~10V:

    https://www.ebay.co.uk/itm/3-7V-240mAh-481540-Li-Polymer-Rechargeable-Cell-Li-ion-LiPo-Battery-for-GPS-MP3/192607481393?hash=item2cd84cee31:g:ncQAAOSwrVRbVv~g

     

    And a charger such as this will charge six cells at once:

    https://www.ebay.co.uk/itm/A100-Multi-Port-Lipo-Battery-Charger-1S-3-7V-LOSI-Charge-Port-for-RC-Boat-Car/273844696735?hash=item3fc26a769f:g:r0cAAOSwE21c2cHA

     

    You just need to make up the plug & socket connections.

     

  10. 39 minutes ago, jpendle said:

    And I'm not sure that I can get Copydex here in the US, although I haven't looked.

     

    Copydex is pretty much the same thing as plain white "liquid latex" as used for stage make up etc. or general latex fabric / carpet adhesive.

    Those are readily available from many places.

     

    This looks to be the same stuff: https://www.homedepot.com/p/Roberts-8-oz-Universal-Carpet-Seam-Sealer-8015-A-4/100077982

     

     

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  11. I'm guessing this is the Wireless World article people keep referring to -

    The magazines are in a public archive so I don't see a problem providing a link to that?

     

    See page 30 of the PDF (Page 333 as shown on the original pages).

    https://www.americanradiohistory.com/Archive-Wireless-World/70s/Wireless-World-1972-07.pdf

     

    The full archive of WW is here, just to give proper credit to the site:

    https://www.americanradiohistory.com/Wireless_World_Magazine.htm

     

    • Like 3
  12. 34 minutes ago, sharris said:

    Has the self-discharge rate in NiMH batteries improved in recent years? 

    Yes, drastically so.

     

    The Eneloop and later Duracell "pre-charged" NiMH cells have incredibly low self discharge and the overall functional life for intermittent use without capacity loss is vastly greater than older types.

     

    Whether you can get PP3 style with that type of cell construction is a different matter, but for AA and suchlike they are fantastic things.

     

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  13. 12 hours ago, 31A said:

    I'm a bit surprised nobody has used e-cigarette technology in this way.  After all they aren't much bigger than a model loco, although I don't know much about what goes on inside them.  I'd've thought it would be possible to use the vapour producing bits of them, without the potentially harmful additives that are put into them.

    That is a brilliant idea!

     

    Use the vaporizer section of one of those with commercial entertainment-grade "fog fluid" rather than the oil based or whatever stuff normally used with model rail smoke systems and it ought to be extremely effective.

     

    And those bulk liquids are very cheap compared to many smoke fluids, as well as having all the appropriate safety data etc. for use in public spaces.

    https://www.gear4music.com/PA-DJ-and-Lighting/Dense-Fog-Machine-Fluid-5L-by-Gear4music/2JR1?origin=product-ads&campaign=PLA+Shop+-+GENERIC&adgroup=GENERIC&medium=vertical_search&network=google&merchant_id=1279443&product_id=118909d1&product_country=GB&product_partition_id=309292131805&gclid=EAIaIQobChMIsJ_UnvXh5QIVxbHtCh0JywYZEAQYASABEgLmV_D_BwE

     

    The only other bit needed would be an ultra-miniature fan or bellows of some sort to force air through the vaporiser?

     

    Edit - possibly something like this, 10mm square by 3mm thick?

    https://www.alibaba.com/product-detail/Mighty-Mini-SUNON-Micro-1003-10x3_60170338698.html

    http://www.sunon.com/pro2_page.php?pkid=6

     

    Or even smaller, 9mm centrifugal?

    https://www.alibaba.com/product-detail/Mighty-Mini-SUNON-Maglev-0903-9x3_62009823719.html?spm=a2700.details.deiletai6.9.48bb545ej5qWHQ

     

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  14. A normal single-use PP3 has six "1.5V" cells, so starts out at around 9V but will steadily drop in voltage over its life and is at about 6V when genuinely flat, just before the voltage drops away rapidly.

     

    Rechargeable PP3s typically use seven or eight NiCD / NiMH cells. That gives a nominal voltage of 8.4V or 9.6V, but with a real voltage range (just taken off charge when full, to empty) of almost 10.5V or 12V respectively, and again down to 1V per cell so 7V / 8V.

     

    Eight cell ones are high enough voltage to be out of spec on things designed for normal PP3s.

     

    Some things that use 7805 type voltage regulators will fail at around 7V, but either type should maintain that if in good condition.

     

     

    "Memory effect" can cause nickel based cells to appear flat before they genuinely are, as the internal resistance increases if an attempt is made to discharge them below their normally-used range.

     

    That can be eliminated by discharging them completely via a resistive load, which is completely safe when individual cells can be accessed but risky with an assembled battery, as any weak cells can end up reverse polarised..

     

    If you want to try it with any batteries that are otherwise unusable, just connect a filament lamp across the battery and leave it for a few days.

    Then recharge, allowing at least 40% over the theoretical minimum time to reach full on whatever charger you use, unless they get hot.

     

  15. Also have a look on "Thingiverse" for printable items you can adapt:

    https://www.thingiverse.com/

     

    eg. Search for buildings or architecture.

     

    One I found quickly - a "building kit" 

    https://www.thingiverse.com/thing:645328

     

    Note that you can re-scale objects in the slicer program if they are not the correct size for your requirements.

    Just use the same scale figure on all the parts and they should all fit together at any reasonable scale.

     

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